Socialism and communism seem good on paper, but in reality there are many problems associated with it. You HAVE to take from some source, and it just feels like you're incentivizing people to work less. The rich can get taxed, sure, but everybody wants to be rich, right? Greed will reign supreme in all cases, and for those who actually achieve that upper-class level, they'll be PUNISHED for the hard work.
Capitalism equally seems good on paper, but in reality there are many problems associated with it.
As with any form of bigotry (such as racism, sexism, homophobia), there are advantages to being in the priveleged class that give those an unequal boost at life.
There are many that work longer and harder and receive barely enough to sustain themselves. Look at the use of foodstamps in the USA. How is that anyone working full time should need to rely on govt subsidies to survive?
The Magna Carta, created in 1215, was an important step in creating freedom for the serfs of England. The basic truth in equality of birth has not changed.
The very idea of personal freedom is threatened by both capitalism AND socialism as we know it. There is no freedom when some people are "more equal than others".